Cell phone amplifier

[spirithorse]

Greetings!
I thought I would try a simple pattern cut today and was immediately
set back with questions.
This is the pattern link https://www.stevedgood.com/passiveamp.pdf

I am unsure of weather the third board, listed as a 3/4" stock, is supposed
to have the phone cut out area. If cut out, it does not really align with the
sound chamber but, if it is not cut out, the phone is just balanced on 1/2"
from the two 1/4" pieces. The phot makes it look like it is cut out and
the sound hole goes through that board.

That brings up the question of the sound hole. There is no measurement
listed for the size forstner bit Steve used.

I experimented with cutting the pattern and the results for amplifying my phone
were non-existent.
Did anyone else cut this pattern?
Thanks and God Bless!  Spirithorse

[KCSteve]

In looking at the pattern the key seems to be the U shaped cut in the middle layer - it needs to start where your phone's bottom speaker is.  It conducts the sound over to the hole drilled in the front 1/4" layer.
Steve said this was for a particular iPhone so you have to adjust for your phone.  If the speaker holes on the bottom won't line up with the middle 1/4" layer then you'll have to put a 'dent' in the back layer to get them lined up.